This invention is related to the field of munitions, and more particularly toward in-flight corrections of these munitions.
There are known methods of correcting the trajectory of in-flight munitions. One such method is described in U.S. Pat. No. 5,131,602, entitled xe2x80x9cApparatus for Remote Guidance of Cannon-Launched Projectiles.xe2x80x9d Another method is described in U.S. Pat. No. 5,647,558, entitled xe2x80x9cMethod and Apparatus for Radial Thrust Trajectory Correction of a Ballistic Projectile,xe2x80x9d issued to the present inventor.
One known method of correcting the trajectory of munitions in-flight is with aerodynamic control surfaces. However, a fairly stable platform is essential for this method, and a spinning platform would make in flight direct control via this method extremely difficult. Further, such control surfaces often have a limited effect in the thin ambient air encountered at high altitudes.
Another known method uses impulse motors or rockets, usually acting nearly through the gravimetric center of gravity of the munitions in flight, perpendicular to the longitudinal axis of such a munition(s), and angularly oriented such that the equal and opposite reaction will create the desired correction. In this instance, commonly used apparatus to achieve trajectory correction consists of an impulse motor or rocket, or a series of impulse motors or rockets that may be fired once, or more than once, to produce the desired correction to the trajectory of the munition(s), in question or at least a portion of that correction thus improving the accuracy and lethality of the munition(s).
In this method, the impulse means generally consists of a form of propellant in solid, granular, liquid or gaseous form. The propellant is converted from a more solid form to a more gaseous form, which greatly increases it material volume. This volumetric explosion creates an equal and opposite reaction to effect the in-flight trajectory correction.
The propellant requires a particular means of operational apparatus and containment, including the appropriate nozzles, internal reactive structures and the like. Such apparatus and containment means, including all those items well known in the art, utilize valuable internal pay load volume. This volume utilization is most ideally used to contain the munitions lethality means, including submunitions and various lethal charges.
As an introduction to this field of invention, it is useful to understand some of the mathematical principles involved. In one hypothetical example, an in-flight munition, with a mass of 50 kg and traveling at a speed of 200 m/s, is 5000 m from the desired target. In this example, it has been determined, by some means (via on-board INS, global positioning system, ground based active or passive radar, or some other means), that a correction of 1000 m is required.
D=5000 m=distance from target 
Dc=1000 m=correction distance 
V=200 m/s=velocity 
xe2x80x83D/Dc=0.2 M=50 kg
Vc=transverse velocity correction=V(Dc/D)=40 m/s 
E1=energy to achieve trajectory correction=Vc(M)=2000 Ns 
E2=energy content of ammonium perclorate (propellant)=2500 Ns/kg 
E1/E2=gravametric quantity of propellant as a function of Ns/kg=800 g 
Therefore, 800 g of ammonium perclorate and fuel would need to be activated in a specified direction to correct the trajectory of the munition such to hit the desired target.
The material used for these rapidly expanding propellants for trajectory correction of in-flight munition(s) may fall into three main categories as follows:
Gaseous expansion propellant materials of the type described in the hypothetical example above.
Deflagration materials, which could be considered as a muted or toned down explosive, could also be used. This material can possess orders of magnitude more available energy per volumetric unit than the gaseous propellant as described in the example above. Therefore, less volume would be required within the in-flight munition(s) to effect the same reaction. However, one drawback is the size of the containment apparatus and the reactive structures and other required apparatus to support such deflagration materials, with their massive forces of expansion. Such drawbacks may very well outweigh the obvious benefits of deflagration materials.
Detonation materials could also be used in lieu of ordinary propellants or deflagration materials. Detonation materials in fact describe explosives, and can increase the force provided exponentially, as opposed to ordinary propellants and even deflagration materials.
However, the use of deflagration and detonation materials is difficult to control and may very well destroy the munition in-flight rather than correct the trajectory of such flights.
These and other drawbacks exist.
An object of the invention is to overcome these and other drawbacks in existing devices.
It is an object of the invention to affect the necessary munition(s) correction while in-flight, resulting in increased accuracy and utilization of a minimum of internal munitions volume.
It is another object of the invention to decrease the volume occupied by the trajectory correction means and apparatus, and subsequently increase the volume available for on board lethal cargo payload of all sorts, thereby offering increased accuracy together with substantially increased lethality.
It is another object of the invention as further described herein to utilize the vastly increased power of deflagration or detonation materials, while maintaining impulse control, without destroying the munition whose trajectory is being corrected, and without increasing the trajectory correctable munition(s) cost or complexity.
It is another object of the invention to create trajectory correctable munitions whose trajectory correction means utilize substantially less internal munitions volume than munitions corrected with ordinary propellants as described in the example in the Background of the Invention, with the result being substantially increased lethality on target with no increased cost, while still providing at least a 50% to 95% improved cost to kill ratio, and a vastly decreased logistical tail because less munitions, guns, personnel and other military equipment will be required to accomplish the same mission without the benefits provided by this invention.
It is another object of the invention to provide an in-flight trajectory correction apparatus, wherein a slug is propelled away from a munition at a desired speed and direction to correct the trajectory of the invention.
It is another object of the invention to construct the slug of a heavy metal, such as depleted uranium, and be propelled by a deflagration material or a detonation material.
To accomplish these and other objects of the invention, improved apparatus and means for trajectory correction are disclosed.
An device for correcting the in-flight trajectory of a munition consists of an impulse motor assembly body. The slug and propellant are located within the impulse motor assembly body. In one preferred embodiment, the slug is made of a heavy metal, such as depleted uranium, while the propellant is made of a deflagration material or detonation material.
When a trajectory correction of the munition is desired, the propellant is activated and the slug is shot out of the munition. This force causes a correction in the trajectory of the munition.